1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method thereof.
2. Description of the Related Art
As a conventional technology serving as a background of the present invention, there is a technology described in Japanese Patent Laid-Open Publication No. 2003-318413 “High-Breakdown-Voltage Silicon Carbide Diode and Manufacturing Method Thereof” as Patent Document 1 filed by the applicant of this invention.
In the conventional technology described in Patent Document 1, on a first main surface of a semiconductor base in which an N− silicon carbide epitaxial layer is formed on an N+ silicon carbide substrate, a P+ polycrystalline silicon layer is formed, in which a band gap is different from that of the semiconductor base, and a conduction type is different from that of the semiconductor base. The N− silicon carbide epitaxial layer and the P+ polycrystalline silicon layer form a heterojunction. Here, the P+ polycrystalline silicon layer is connected to an anode electrode, and on a back surface of the N+ silicon carbide substrate, a cathode electrode is formed. Note that symbols + and − represent a high density and a low density, respectively.
The semiconductor device of the conventional technology with the configuration as described above functions as a diode. Specifically, when a potential of the anode electrode is higher than a potential of the cathode electrode, a forward current flows through the diode, and otherwise, a current is inhibited from flowing therethrough.